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query_list.ts
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query_list.ts
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/**
* @license
* Copyright Google Inc. All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import {Observable} from 'rxjs/Observable';
import {EventEmitter} from '../event_emitter';
import {getSymbolIterator} from '../util';
/**
* An unmodifiable list of items that Angular keeps up to date when the state
* of the application changes.
*
* The type of object that {@link ViewChildren}, {@link ContentChildren}, and {@link QueryList}
* provide.
*
* Implements an iterable interface, therefore it can be used in both ES6
* javascript `for (var i of items)` loops as well as in Angular templates with
* `*ngFor="let i of myList"`.
*
* Changes can be observed by subscribing to the changes `Observable`.
*
* NOTE: In the future this class will implement an `Observable` interface.
*
* ### Example ([live demo](http://plnkr.co/edit/RX8sJnQYl9FWuSCWme5z?p=preview))
* ```typescript
* @Component({...})
* class Container {
* @ViewChildren(Item) items:QueryList<Item>;
* }
* ```
* @stable
*/
export class QueryList<T>/* implements Iterable<T> */ {
private _dirty = true;
private _results: Array<T> = [];
private _emitter = new EventEmitter();
get changes(): Observable<any> { return this._emitter; }
get length(): number { return this._results.length; }
get first(): T { return this._results[0]; }
get last(): T { return this._results[this.length - 1]; }
/**
* See
* [Array.map](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map)
*/
map<U>(fn: (item: T, index: number, array: T[]) => U): U[] { return this._results.map(fn); }
/**
* See
* [Array.filter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter)
*/
filter(fn: (item: T, index: number, array: T[]) => boolean): T[] {
return this._results.filter(fn);
}
/**
* See
* [Array.find](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find)
*/
find(fn: (item: T, index: number, array: T[]) => boolean): T|undefined {
return this._results.find(fn);
}
/**
* See
* [Array.reduce](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce)
*/
reduce<U>(fn: (prevValue: U, curValue: T, curIndex: number, array: T[]) => U, init: U): U {
return this._results.reduce(fn, init);
}
/**
* See
* [Array.forEach](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach)
*/
forEach(fn: (item: T, index: number, array: T[]) => void): void { this._results.forEach(fn); }
/**
* See
* [Array.some](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some)
*/
some(fn: (value: T, index: number, array: T[]) => boolean): boolean {
return this._results.some(fn);
}
toArray(): T[] { return this._results.slice(); }
[getSymbolIterator()](): Iterator<T> { return (this._results as any)[getSymbolIterator()](); }
toString(): string { return this._results.toString(); }
reset(res: Array<T|any[]>): void {
this._results = flatten(res);
this._dirty = false;
}
notifyOnChanges(): void { this._emitter.emit(this); }
/** internal */
setDirty() { this._dirty = true; }
/** internal */
get dirty() { return this._dirty; }
/** internal */
destroy(): void {
this._emitter.complete();
this._emitter.unsubscribe();
}
}
function flatten<T>(list: Array<T|T[]>): T[] {
return list.reduce((flat: any[], item: T | T[]): T[] => {
const flatItem = Array.isArray(item) ? flatten(item) : item;
return (<T[]>flat).concat(flatItem);
}, []);
}